"The Spiral Stair or Vice: its origins, role and meaning in medieval stone castles: Thesis submitted in accordance with the requirements of the U

"The Spiral Stair or Vice: its origins, role and meaning in medieval stone castles: Thesis submitted in accordance with the requirements of the University of Liverpool for the degree of Doctor of Philosophy by Charles Ryder February 2011" (https://core.ac.uk/download/pdf/9632028.pdf https://core.ac.uk/download/pdf/9632028.pdf) I can't find anything specific about the theory, except quotes like "Simpson notes the presence of spiral stairs throughout this work, though sadly, when describing Colchester Castle, Essex, he falls into the old trap of claiming that the spiral clockwise spiral stair aids the defender" and a reference to a different 1854 source mentioning it.